New Data on the Structure and Formation Conditions of the Olenegorsk Ophiolite Complex in the Kamchatskii Mys Peninsula (Kamchatka)

摘要

During field works in the Kamchatskii Mys Peninsula (eastern Kamchatka) carried out in 2002, we obtained new data on the internal structure and geological position of the Olenegorsk gabbro pluton, which represents a fragment of the disintegrated ophiolite complex within the island-arc terrane of the Kamchatka thrust-fold zone. These data clarify geodynamic formation conditions of the complex and allow better understanding of processes in island arc systems and their development before their incorporation into the structures of the Pacific Ocean framing. The structure of the Kamchatskii Mys Peninsula includes several allochthonous complexes overlain by the Miocene-Pliocene and Pliocene-Quaternary formations. They are composed of the Aptian-Cenomanian effusive-siliceous-carbonate rocks of the Afrika Complex, Campanian-Maestrichtian tuffogene-siliceous and terrigenous rocks of the Pikezh Complex, Paleocene-Eocene volcanogenic-terrigenous sediments of the Kamensk Complex, serpentinite melange, serpentinized peridotites of the Mount Soldatskaya Pluton, and gab-broids, gabbro-dolerites, dolerites, and basalts of the Olenegorsk Pluton. The rocks of the Olenegorsk Pluton form the lower structural element in this thrust packet. They have tectonic contacts with Paleogene and Upper Cretaceous formations and only sometimes are overlain by the Paleocene-lower Eocene Kamensk Complex.